Development of a Competitive Indirect Enzyme-Linked Immunosorbent Assay for Screening Phenylethanolamine A Residues in Pork Samples

Rapid and High-Throughput Determination of Sixteen β-agonists in Livestock Meat Using One-Step Solid-Phase Extraction Coupled with UHPLC-MS/MS

β-agonists are illegally added to animal feed because they can greatly increase carcasses' leanness, which impairs the safety of animal-derived foods and indirectly endangers human health. This study aimed to develop an ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for determining sixteen β-agonists in livestock meat. The homogenized samples were subjected to enzymatic hydrolysis using β-glucuronidase/sulfatase at 40 °C for 2 h, extracted with acetonitrile containing 1% acetic acid (v/v), and purified by the one-step Qvet-AG extraction column. The residue was redissolved by 0.1% aqueous formic acid/methanol (9:1, v/v) after blow-drying by nitrogen, and then determined by UHPLC-MS/MS. The results demonstrated that the well linearity was in the range of 0.1-50 μg/L with the correlation coefficient (R²) ≥0.9928, and the limits of detection (LOD) and quantification (LOQ) were 0.01-0.11 μg/kg and 0.04-0.38 μg/kg, respectively. With intraday and interday relative standard deviations (RSDs) being less than 10%, the average recoveries of pork, beef, and lamb at various spiked levels ranged from 62.62-115.93%, 61.35-106.34%, and 62.00-111.83%, respectively. In conclusion, the established method is simple, efficient, sensitive, and suitable for the simultaneous detection of several β-agonist residues in livestock meat.

A Fast Method for the Simultaneous Analysis of 26 Beta-Agonists in Swine Muscle with a Multi-Functional Filter by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

A rapid and simplified sample preparation method was developed for the simultaneous determination of 26 beta-agonists in swine muscle using a multi-functional filter (MFF) based on quick, easy, cheap, effective, rugged, and safe methods (QuEChERS). MFF integrated the cleanup and filter procedures, thereby significantly improving the efficiency of sample preparation compared with traditional solid-phase extraction. The sample was processed via enzymatic hydrolysis, purified with the optimized MFF containing 150 mg magnesium sulfate, 50 mg PSA, and 50 mg C18, and then analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry. All procedures can be completed in 6.5 h. Good linearity (R2 > 0.99) was detected in all analytes. The recoveries ranged from 71.2% to 118.6%, with relative standard deviations (RSDs) of less than 18.37% in all spiked concentrations. The limits of detection (LOD) and the limits of quantitation (LOQ) were 0.01–0.10 and 0.10–0.50 μg/kg, respectively. The decision limit (CCα) and detection capacity (CCβ) values fluctuated in the range of 3.44–25.71 and 6.38–51.21 μg/kg, respectively. This method is a good alternative for detecting beta-agonist residues in swine muscle and can be successfully applied to the national risk monitoring of agro-product quality and safety in China.

The determination of β-agonist residues in bovine tissues using liquid chromatography-tandem mass spectrometry

We aimed to develop a rapid, simple and reproducible method based on LC-tandem mass spectrometry (LC-MS/MS) to analyze β-agonist residues (clenbuterol, zilpaterol, ractopamine and isoxsuprine) in bovine tissues. The method was validated in accordance with the European Council Decision 2002/657/EC. The samples were homogenized, and then 10 mL of an acetate buffer was added to a 5-g sample. The sample was then centrifuged at 12,000 rpm and filtered. Sodium hydroxide (2 m) was added to adjust pH of the sample that was centrifuged again. The extract was filtered through a solid-phase extraction column. The residue was re-dissolved in 250 μL acetonitrile and then subjected to LC-MS/MS. The separation was done on a C₁₈ column. The mobile phase consisted of 0.1% formic acid in deionized water and 0.1% formic acid in methanol. The mean recoveries of β-agonists were in the range of 84.3%-119.1% with relative standard deviations (%RSDs) of 0.683%-4.05%. Decision limits and detection capabilities of the analytes ranged from 0.0960 to 4.9349 μg/kg and from 0.0983 to 5.0715, respectively. This method was used to detect four β-agonists in 100 bovine muscle, 100 liver and 100 kidney tissues from a slaughterhouse. No residue was found above the maximum residue limit level.

Colloidal Gold Immunochromatographic Strip Assay for the Detection of Azaperone in Pork and Pork Liver

In this study, a highly sensitive and specific monoclonal antibody (mAb) against azaperone was produced. The mAb belonged to the IgG2b subtype and its half maximal inhibitory concentration (IC₅₀) was 0.46 ng/mL. The limit of detection value was 0.081 ng/mL and the linear range (IC₂₀-IC₈₀) was 0.165-1.29 ng/mL. Based on this anti-azaperone mAb, a colloidal gold immunochromatographic strip assay method was established for the detection of azaperone in pork and pork liver samples. For pork samples, the cutoff value of the colloidal gold immunochromatographic strip assay was 10 ng/g, and the cutoff value was also 10 ng/g in pig liver samples. This colloidal gold immunochromatographic strip assay is a rapid, simple, and practical method for the detection of azaperone in pork and pork liver samples available in markets.

Simultaneous determination of β-agonists on hexagonal boron nitride nanosheets/multi-walled carbon nanotubes nanocomposite modified glassy carbon electrode

β-Agonists are illegally consumed in various products such as food and animal and effect the nutrition distribution owing to change of body fat. In addition, they result in acute poisoning and several symptoms such as muscular tremors and nervousness. A new electrochemical approach based on two-dimensional hexagonal boron nitride (2D-hBN) nanosheets decorated functionalized multi-walled carbon nanotubes (f-MWCNTs) was presented for simultaneous determination of β-agonists such as phenylethanolamine A (PEA), clenbuterol (CLE), ractopamine (RAC) and salbutamol (SAL) in urine samples. X-ray diffraction (XRD) method, Raman spectroscopy, scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used characterizations of nanomaterials. After that, 2D-hBN/f-MWCNTs nanocomposite modified glassy carbon electrode (GCE) was prepared for simultaneous determination of β-agonists. 1.0 × 10^-12-1.0 × 10^-8 M and 1.0 × 10^-13 M were founded as the linearity range and the detection limit (LOD) for PEA, CLE, RAC and SAL. Finally, the prepared electrochemical sensor was used for urine sample analysis in presence of ascorbic acid (AA) and uric acid (UA).

A Dual-Color Quantum Dots Encoded Frit-Based Immunoassay for Visual Detection of Aflatoxin M1 and Pirlimycin Residues in Milk

Mycotoxins and antibacterial agents are the main chemical hazards that lead to several health problems. Nowadays, multiplex immunoassay is a primary goal throughout the world. Here, aflatoxin M₁ and pirlimycin were selected as models, and a novel dual colorimetric encoded frit-based immunoassay was developed for simultaneously screening of aflatoxin M₁ and pirlimycin residues in milk. This multiplex frit-based immunoassay combined two monoclonal antibodies to extend the spectrum of analytes and to enable detection of two classes of analytes in a single test. The cutoff values were 0.02 μg/kg for aflatoxin M₁ and 0.5 μg/kg for pirlimycin, which satisfied the requirement to measure the maximum residue levels. The novel colorimetric frit-based immunoassay has the advantage of high throughput, short analysis time, reduced overall cost per assay, and can be used as a rapid screening technique for simultaneously detecting aflatoxin M₁ and pirlimycin residues in milk.